Air-cooled engine for aircraft



Dec, 22, 1931. w FlSCHER 1,838,054

AIR COOLED ENGINE FOR AIRCRAFT Filed Sept. 16, 1929 gwuwnkoz Wflhelm Fischer 346. 4 v as? Talented Dec. 22, 1931 riscm, O B H AIR-0001331) ENGINE FOB Application filed September is, 1929. Serial No. asaaas.

This invention relates to internal combust1on engines, and it has particular relation to a device for facilitating the circulation of air about the cylinders of air-cooled engines of aircraft or other propelled vehicles.

The principal object of the invention is to reduce the air resistance of the cylinders of air-cooled engines.

Another object of the invention is to improve the cooling of the leeward portions of the cylinders of air-cooled engines;

Another object of the invention is to imrove carburetion of the fuel in air-cooled internal combustion engines. 1

- Inasmuch as air-cooled internal combustion engines must be exposed to an air stream in order to efiect the necessary dissipation of heat, they cause considerable air resistance which should be maintained at a minimum. Stream-line cowlings have been disposed about such engines for the purpose of reducing the air resistance thereof. However, these cowlings must leave the finned cylinder barrels of the engine uncovered and ex osed to an air stream of highvelocity in or er to secure the necessary dissipation of heat.

Experiments conducted in a wind tunnel, wherein acylindrical body was so exposed to the air stream that the principal axis of the body was disposed at right. angles to the air stream, have shown that the air resistance can be materially reduced by employing a suction producing means to draw air from the boundary layer of the body. By employing a suction producing means 1n this manner the air is directed closely along the circular contour of the cylindrical body, thereby decreasing the eddies and in consequence, reducing the air resistance of the body.

According to this invention, which is based upon these experiments, the air is drawn by suction away from the leeward portions of cylinder barrels of anair-cooled engine for the purpose of decreasingsthe air resistance of the cylinder barrels and to improve the air cooling of the leeward portions of the barrels. Another important feature of my invention 15 to utilize, for the purpose described above,

the pumping action of the cylinders during admission strokes either alone or in connection with thepumping action of a fan impeller or a supercharger as incorporated in the design of modern air-cooled aero engines.

This arrangement not only simplifies the embodiment .of my invention but adds another advantage to it, namely: the warm air drawn from the cylinders is thus directed into the carburetor and facilitates the carburetion of the fuel.

For a better understanding of the invention, reference may now be had to the accompanying drawings, forming a part of the specification, of which;

- Figu elevational view of an internal combustion engine having a cooling device embodying the invention mounted thereon;

Figure 2 is a fragmentary front elevational 0 view of an engine'shown by Figure 1;

Figure 3 is a fragmentary elevational view of one of the engine cylinders having two suction tubes mounted adjacent thereto;

Figure 4 is a fragmentary side-elevational view of an engine having a cooling device 7 inders and are provided with openings 18.

It will be observed that one or more conduits 17 can be located adjacent each cylinder, as shown by Figures 2 and 3. An air intake connection 20 of a conventional carburetor 21 is secured to the manifold 16,

and conduit connections 25 also lead from the carburetor to the cylinders 13 for the purpose of transmitting suction forces from the cylinders to the carburetor and thence to the conduits 17.

Air is drawn by suction from the leeward re 1 is a diagrammatic fragmentary A manifold 16,

portion of each cylinder by utilizing the suction stroke of the pistons of the engine, or

by other suitable means. Since the air that is drawnaway from the rear of the cylinders 13 and directed into the carburetor 21, is heated by the cylinders, the carburetion of fuel is facilitated and the air-fuel mixture is rendered more favorable for proper combustion in the engine.

In Figures 3 and 4 the operation and construction shown is similar to that described above, and since the only material difference is in the construction of the engine wherein the cylinders shown by the later figures are arranged in series, the same numerals are employed to designatesimilar elements and the same description applies thereto.

Although I have illustrated only the preferred forms of theinventio'n and have described those forms in detail, it will be apparent to those skilled in the art that the invention is not so limited, but that various modifications may be made therein without departing from the spirit of the invention or from the scope of t e appended claims.

. What I claim is: v

1. In an air-cooled engine havinga cylinder normally exposedto an air stream, a

suction producing means independent of the initiation of said air stream, the suction producing means touching the boundary layer of air adjacent the leeward portion of the cylinder for 'drawin said boundary layer away from the cylin er.

2. In an internal combustion engine having cylinders normally exposed to an air stream, hollow members having openings communicating with the boundary layer of air about the leeward portions of the c l- 40 inders, and suction producing means or drawing the boundary layer of air away from the leeward portions of the cylinders through the hollow members.

I 3. In an air-cooled engine having-cylinders normally exposed to an air stream, hollow members having openings disposed adjacent the leeward portions of the cylinders and communicatingwith the boundary layers of air about the cylinders, a carburetor, a 11181111,

fold connected to the hollow members and to the carburetor and suction producing means for drawing air from the leeward portions of the cylinders through the manifolds to the carburetor. I

56 4. In an air-cooled engine having cylinders normally exposed to an air stream, a manifold having connections communicating with the leeward surface portions of the cylinders,

a carburetor having an intake connection 5 and suction producing means for drawing air from the leeward surfaces of the cylinders and directing it to the air intake con nection, said suction-producing means ineluding connections to the interior of the cylmders. r

'5. In an internal combustion engine having a cylinder normally exposed to an air stream, means establishing communication between the interior of the cylinder and the leeward surface thereof for utilizin the suction of the cylinder to draw air rom the boundary layer of air about said leeward surface.

6. In an air-cooled engine haying cylinders normally exposed to an air stream, hollow members disposed adjacent the leeward portions of the cylinders, and means for utilizing the suction produced in the cylinders for drawing the boundary layer of air awa from the surfaces of the cylinders through the hollow members.

In witness whereof, I have hereunto signed my name,

Signed at Akron, in the county of Summit and State of Ohio, U. S. A., this 3d day of September, 1929.

. WILHELM FISCHER. 

